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Gas Volume Converters

« Volume conversion device » is terminology to designate what was previously called a volume corrector. those instruments can give the real volume consumption (Vb) by measuring the raw volume (Vm), the pressure at which it was distributed and the gas temperature


Those devices destined to B to B relationships, have to comply with the EN12405 regulation as well as the MID directive.

Three types of conversion exist :

Only the temperature is measured whereas the pressure and pressure compressibility factor are fixed parameters.
Temperature and pressure are measured and only the pressure compressibility factor is fixed.
Temperature and pressure are measured, Also the pressure compressibility factor is calculated according to a specific formula (SGERG, AGA8, AGANX19…)

SIS has developed its new volume conversion device ENVOL based on European directive 2014/32/UE (MID: Measuring Instruments Directive), ENVOL complies with the EN12405-1 standard and is Certified as such.

As most of our customers wanted the device to be installed in Gas area, we have conceived the product in order for it to be certified ATEX Area 1 (Intrinsic Safety).


conceive the product using the security against explosion elements, avoid that devices and protection system produce ATEX and prevent the inflammation of ATEX, whether the source is electrical or not.

ENVOL is a Volume Conversion Device, used in combination with a counter to measure first and second class gas as per the EN437 directive.

ENVOL in its PTZ configuration enables the use of different conversion methods to calculate the Gas compressibility factor: SGERG88, AGA 8 Full, AGA 8 -1, AGA8 -2, AGA NX 19, by table (Azotes).

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  • EMMER service
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  • Engie